Roller-type reducing apparatus

ABSTRACT

A roller-type reducing apparatus comprising reducing rollers mounted within a housing for rotation in opposite directions. The reducing rollers comprise a plurality of reducing discs having different diameters and placed in a side-by-side relationship. There are provided reducing discs with fine serrations and reducing discs with coarse serrations, with comminuting discs with fine serrations having a diameter smaller than that of reducing discs with coarse serrations.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to roller-type reducing apparatuscomprising reducing rollers mounted within a housing and adapted to berotated in opposite directions.

[0003] 2. Description of the Related Art

[0004] Roller-type size reducing apparatus of the inventive kind is usedfor processing brittle low-abrasion materials, preferably deep-freezeembrittled spent tire fragments, industrial rubber product waste as wellas plastics-metal/fiber composites.

[0005] Spent motor vehicle tires constitute a rich source of rawmaterials. In the prior cryogenic process, the rubber of such tires issupposed to be granulated in the embrittled condition for conversioninto a reusable secondary raw material which can be returned toproduction processes.

[0006] The rubber granulates and rubber crumbs obtainable in priorcryogenic shredding and reducing plants have turned out to haveproperties which make them unsuitable for processing and recycling. Thegranules are too big; they contain excessive amounts of foreignmaterials that cannot be separated from them any longer—such as steelreinforcements or textile fibers—and are non-uniform in consistency.Scrap rubber of this nature is not suited for large-scale recycling andraises considerable technical problems.

SUMMARY OF THE INVENTION

[0007] The object of the present invention is to provide for reducing ofthe type initially described which enables brittle low-abrasionmaterials—preferably cryogenically embrittled scrap rubber—to beprocessed into granulates and powders having a uniform consistency.

[0008] This object is attained by using reducing rollers each comprisinga plurality of reducing discs placed side by side and having differentdiameters. In another embodiment, the reducing rollers each comprise aplurality of reducing discs placed side by side and having differentdiameters and peripheral serrations.

[0009] Further, the above object is attained by means of roller-typereducing assembly comprising reducing rollers mounted within a housingfor rotation in opposite directions, such rollers comprising differentlyserrated discs of different diameters and mounted in alternating fashionon associated shafts in such a manner that large-diameter discs of oneroller face the small-diameter discs of the other roller.

[0010] In addition, the finely serrated reducing discs are provided tohave a smaller diameter than the larger-diameter reducing discs.

[0011] The aforesaid measures result in roller-type reducing assemblysuited for reducing embrittled scrap rubber into rubber granulate andrubber powder. By its design and the materials used for its fabrication,the inventive apparatus will support the special loads and stressesoccurring in low-temperature operation at approximately 100°C. belowfreezing.

[0012] The rubber component is reduced into a granulate having arelatively uniform granule structure. Most of the fiber and steelcomponent remains in an unreduced condition so that they are easilyseparated.

[0013] The reducing assembly has a closed-loop speed-regulated drive sothat the reduction process can be matched closely to the quality of thescrap rubber to be processed. As the reducing gap is variable in width,it is possible to produce a rubber granulate which has a predeterminedgranule size, granule surface and granule structure. The speeds of theoppositely rotating rollers can be varied independently.

[0014] The entire reducing system is arranged for rapid and easy repairand maintenance. To this end, stationary relocating means are providedfor relocating the machine components from an operating position to aservicing position using a small number of manual operations. Hoistsinstalled above the servicing position are provided to facilitatenecessary repairs.

[0015] The reducers are thermally and sound-insulated. In its entirety,the system is encapsulated for operation in a substantially dust-freemanner.

[0016] Additional advantageous measures are described in the dependentclaims. The invention is illustrated in the attached drawings and isdescribed in greater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a section view of roller-type reducing assemblycomprising two oppositely rotatable reducing rollers consisting ofintegrally joined and differently serrated reducing discs;

[0018]FIG. 2 is a section view of a finely serrated reducing disc and ofa coarsely serrated reducing disc as well as the details of a reducingdisc assembly according to FIG. 1; and

[0019]FIG. 3 is a plan view of the reducing disc assembly according toFIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

[0020] As shown in FIG. 1, roller-type reducing assembly 10 essentiallycomprises a base frame 11 having a housing 12 thereon. Housing 12accommodates two oppositely rotatable reducing roller 13 and 14 mountedfor rotation on reducing roller bearings 16.

[0021] Reducing rollers 13 and 14 are driven by reducing roller drives15 and 15 a and supported by reducing roller spring assembly 22.

[0022] As shown in FIGS. 2 and 3, reducing rollers 13 and 14 eachconsist of a plurality of reducing discs 13 a and 14 a placed on commonshafts 27 and 27 a, respectively.

[0023] Reducing discs 13 a have a smaller diameter 25 while reducingdiscs 14 a have a somewhat greater diameter 24. Reducing discs 13 a, 14a are integrally joined, with smaller-diameter reducing discs 13 aoffset from greater-diameter reducing discs 14 a by an offset 20.

[0024] On their radially outer surfaces, greater-diameter reducing discs14 a have coarse peripheral serrations 17 and smaller-diameter reducingdiscs 13 a have fine peripheral serrations 18. Each one of reducingrollers 13, 14 comprises a plurality of smaller-diameter reducing discs13 a with fine serrations 18 and a plurality of greater-diameterreducing discs 14 a with coarse serrations 17, the aforesaid discs beingprovided in an alternating relationship and being integrally joined toeach other.

[0025] There is provided between reducing rollers 13 and 14 a reducinggap 19, which is made to be variable by reducing gap width adjustingmeans 21 shown in FIG. 1.

[0026] Offset 20 causes each greater-diameter reducing disc 14 a havingcoarse serrations 17 to be placed face to face with a smaller-diameterreducing disc 13 a having fine serrations 18. Said serrations 17 and 18are provided on the radially outer surfaces of the respective reducingdiscs 14 a, 13 a and have axial tapers 23 on both sides.

[0027] Tapers 23 impart to the reducing gap 19 a zigzag configurationwith a trapezoidal shape in plan view. This arrangement results in thereduction of cryogenically embrittled scrap rubber into granules havingthe flaky surface structure needed for further processing. A liquiddeep-freeze coolant—preferably liquid nitrogen—having a temperature ofapproximately 190° K may be injected in housing 12 while reduction is inprogress.

[0028] Relocating means 26 allows reducing assembly 10 to be movedeasily from an operating position to a servicing position. Any necessaryrepairs are facilitated by hoisting means (not shown) mounted above theservicing position. Reducing assembly 10 is encapsulated in housing 12for thermal and noise insulation and substantially dust-free operation.

[0029] Thus, there has been disclosed a roller-type reducing apparatuswith reducing rollers mounted within a housing for rotation in oppositedirections. The reducing rollers are comprised of a plurality ofreducing discs, the discs having different diameters. The discs alsohave different sized serrations for assisting in sorting scrap rubber.

[0030] Whereas the present invention has been described with respect tospecific embodiments thereof, it will be understood that various changesand modifications will be suggested to one of ordinary skill in the art,and it is intended that the invention encompass such changes andmodifications as fall within the scope of the appended claims. 10roller-type reducing mill 11 base frame 12 housing 13, 14 reducingroller 13a small-diameter reducing disc 14a great-diameter reducing disc15, 15a reducing roller drive 16 reducing roller bearing 17 coarseserrations 18 fine serrations 19 reducing gap 20 offset 21 reducing gapadjusting means 22 spring means 23 taper 24, 25 diameter 26 relocatingmeans 27, 27a common shaft

what is claimed is:
 1. A roller-type reducing apparatus, comprising: ahousing; a common shaft; a first reducing roller comprising a pluralityof serrated reducing discs; and a second reducing roller comprising aplurality of serrated reducing discs of a diameter less than thediameter of said serrated discs of said first reducing roller; saidfirst and second reducing rollers mounted within said housing forrotation in opposite directions; and wherein said reducing rollers aremounted on said common shaft in such a manner that each serratedreducing disc of said first reducing roller corresponds to one of saidserrated reducing discs of said second reducing roller.
 2. Theroller-type reducing apparatus of claim 1, wherein said serratedreducing discs of said first reducing roller have relatively coarseserrations; and wherein said serrated reducing discs of said secondreducing roller have relatively fine serrations.
 3. The roller-typereducing apparatus of claim 2, wherein said serrations have trapezoidaltapers; and wherein said first and second reducing rollers havedifferent outer diameters.
 4. The roller-type reducing apparatus ofclaim 1, wherein said first and second reducing rollers are mutuallyaxially offset in such a manner that said serrated reducing discs ofsaid first reducing roller rotate in an opposite direction from saidserrated reducing discs of said second reducing roller.
 5. Theroller-type reducing apparatus of claim 1, wherein said serratedreducing discs of said first reducing roller and said serrated reducingdiscs of said second reducing roller form integral reducing rollers. 6.The roller-type reducing apparatus of claim 1, characterized in thatsaid first and second reducing rollers are placed face to face with anintervening variable-width reducing gap between said first and secondreducing rollers.
 7. The roller-type reducing apparatus of claim 6,wherein said variable-width reducing gap extends in zigzag fashion; andwherein said variable-width reducing gap has dimensions similar to orsmaller than in the head portions of said serrated reducing discs ofsaid first and second reducing rollers.
 8. The roller-type reducingapparatus of claim 1, wherein said first and second reducing rollers arerotatable in opposite direction with different speeds; and wherein saidfirst and second reducing rollers have speed-regulating drivesindependent of each other.
 9. The roller-type reducing apparatus ofclaim 8, wherein the speeds of said first and second reducing rollersare independently variable.
 10. The roller-type reducing apparatus ofclaim 1, wherein said first and second reducing rollers have stationaryrelocating means associated therewith.